Field of the Invention
The present invention concerns a brake actuator having a variable volume chamber for service brake actuation, a spring providing for parking or emergency brake actuation, and a fluid operated parking or emergency brake de-actuation chamber.
Description of Related Art
U.S. Pat. No. 5,105,727 to Bowyer concerns a brake actuating mechanism in which a caging rod or tool passes through a pressure plate. An actuator rod is press-fit into a tubular section of the pressure plate to compress an edge of a diaphragm opening against an expanded portion of the tubular section.
U.S. Pat. No. 5,377,579 to Pierce discloses a spring brake actuator in which the cylindrical section of a pressure plate has an inner wall shaped and sized to receive an end of an actuator rod in press-fit engagement.
U.S. Pat. No. 5,507,217 to Plantan discloses an inner diaphragm sealing bead clamped between a pair of diaphragm plates and secured for reciprocal movement by a bolt to a push rod.
U.S. Pat. No. 6,164,187 to Stojic relates to a spring brake actuator with a caging rod passing through a pressure plate into a hollow actuator rod. The actuator rod and a stem of the pressure plate are press-fit together to form an integral unit.
U.S. Pat. No. 6,360,649 to Plantan concerns a spring brake actuator having a lockout bolt assembly having a first portion threaded into a nut fixed relative to the cup shaped portion of a spring brake actuator housing.
Bendix Service Data Publication SD-02-4500 supplies general maintenance and service information on spring brake actuators with piggyback chambers.